1. Field of the Invention
The present invention relates to an apparatus for filtering particulate matter from hydraulic fluids and other dielectric fluids and more particularly to such a filtering apparatus which is adapted to remove fine, particulate matter from hydraulic and other dielectric fluid by the electrostatic floculation of the particles thereof and the capturing of the floc so formed by filter media within the filter.
2. Description of the Prior Art
A number of methods, apparatuses and devices have been previously proposed to remove contaminants, such as particulate matter, from hydraulic fluids, and other dielectric fluids. It has long been known to remove particulate contamination by mechanical filtration. However, such mechanical filtration of particles having a dimension of less than about 5 to 10 microns, known as "fines" in the art, has either been ineffectual due to the relative ease with which such fines travel through the filter medium employed or because the relatively small size of the particles requires filters of considerable bulk and volume to avoid excessive pressure drop within the fluid system due to the necessarily small filter openings required. It has also long been known that some such mechanical filtration also incidentally removes many desirable additives in the fluid.
As an alternative to purely mechanical filtration, a number of different devices have been proposed to remove the fines from the fluids electrostatically by passing contaminated fluid over or through a plurality of electrodes, alternately charged positively and negatively or alternately energized and grounded. In some of the electrostatic filters known in the art, porous filter media are disposed intermediate adjacent electrodes for trapping particulate matter. Filtration is accomplished in one of two or more ways. One manner is the creation of an electric field between two adjacent electrodes whereby the filter medium itself is caused to be charged and to attract the particulate matter to itself. Alternatively, particulate matter is variously charged negatively or positively so that oppositely charged particles will attract to each other to form a floc of larger particulate clumps which may be satisfactorily removed by mechanical filtration.
While many of the prior art electrostatic filters heretofore known and available have been more or less effective for their intended purposes, many of the devices and apparatuses are expensive to construct, bulky or of complicated structure. Further, many of the prior art electrostatic filters are best suited for use in central fluid purifying installations in a substantially stable environment.
Therefore, it has long been known that it would be desirable to have an improved electrostatic filter for removing particulate contaminants from hydraulic fluid and other dielectric fluids and which is adapted for use, for instance, on individual vehicles or the like having fluid systems susceptible of particulate contamination and resultant damage due to wear and blockage of passages caused by such contamination. Moreover, it has long been known that it would be desirable to have such a device which is adapted to be constructed inexpensively and of minimal dimensions; which can be constructed as a disposable, rapidly and easily replaced component in a fluid system; and whose construction permits the deployment thereof within a conventional fluid system without substantial structural modification to the fluid system whereby replacement of the filter requires a minimum amount of labor and time.